Wagtail Custom Revisions Diffing

[skelzor06]

Hello,

I've been using Wagtail for while now and I'm trying to change the behavior of revision diffing. No it turns the RTF into a flat string and compare, right? Would be possible for me, somehow, to maybe override RichTextFieldComparison in my own project to convert html to a markdown and then compare? Since markdown is also a kind of text, maybe it will show a better comparison.

[SebCorbin]

You can try this (markdown_from_html() should be your function converting HTML to Markdown):

# in wagtail_hooks.py
from wagtail.admin.compare import register_comparison_class, TextFieldComparison

class MarkdownComparison(TextFieldComparison):
    def htmldiff(self):
        return diff_text(
            markdown_from_html(self.val_a), markdown_from_html(self.val_b)
        ).to_html()


register_comparison_class(RichTextField, comparison_class=MarkdownComparison)

It will apply to all RTF fields, so if you need more control, you may have to subclass RTF and pass exact_class=True to register_comparison_class

[skelzor06]

@SebCorbin When I edit the page and them compare with a different version, its possible to know if Wagtail is actually using this comparison?

[SebCorbin]

You may add a breakpoint or something like that in this code, but if you need more details, you'll need to dig into the source:

• the revision view
• the comparison made in FieldPanel
• how the panel searches for comparison_class
• where the registry of comparison classes is defined

[laymonage]

or perhaps add some temporary test string in the rendered HTML and see that it shows up in the view...?